Oil on top of pistons

[Los_Control]

To be honest, I think pulling the head is the next step. It is obvious there is oil in the cylinder .... it is a internal problem.

 

You will need to actually open it up and look.

[Ivan_B]

Okay, my "tomorrow" might've been a bit too optimistic, since it take some time to disassemble this engine. The head is off. I did not notice any obvious issues, at this point. I'll replace the stem seals, since I am in there, but will probably be able to leave the valves as is, assuming that they are not leaking. The headgasket also looks normal. Thus far, It seems that the rings are the only thing left. It is somewhat unexpected that the problem only affects one cylinder, though 🙄

 

[Los_Control]

It would be nice to replace the seals and find a obvious leak.

No question it is a small high performance Hot Rod engine that runs under high stress.

 

I wonder if it would do any good to put the plugs back in the head and then fill the chambers with gasoline and check for leaks?

The intake valves on #3 look pretty clean, #4 has a little smudge and #1-#2 are filthy .... seems exhaust valves are always black and sooty, while intakes are clean ... on a good running engine.

 

I wonder if the valves are leaking, can we lap the newer modern engines the same as we could the older engines .... to get the valves to seat?

Or do the seats have to be surfaced with a seat cutting tool?

[kencombs]

I am not familiar with that engine, but some of the newer, smaller, especially turbo-charged engines have issue with the PCV systems that cause similar things.   GM's version especially with the intake changing from vacuum to pressure they have difficulty with reliably managing the fume and oil flow.

[Los_Control]

I looked at your video you shared .... right about the 9 minute mark he was talking about a contraption that operates off of oil pressure and controls the lift/duration of your intake valves .... All I know is he said they go bad and are expensive ....  just something I would want to learn more about.

 

 

[Ivan_B]

4 hours ago, Los_Control said:

I wonder if it would do any good to put the plugs back in the head and then fill the chambers with gasoline and check for leaks?

Do you mean to put the head upside-down and pour some liquid on top of the valves? Sure, this will be part of the testing I'll do. Another part will be to fill the intake/exhaust ports with liquid and see if it leaks out through the valves

4 hours ago, Los_Control said:

seems exhaust valves are always black and sooty, while intakes are clean ... on a good running engine.

The intake valves are at the bottom on my image. The intake valves are clean from the back side (washed with injected gas spray) while dirty at the front. The exhaust are cleaner at the front (due to higher working temp?) but are very dirty on the back. I'll need to clean the back of the valves and the exhaust ports, which is a lot of work I am not looking forward to 🫠

4 hours ago, Los_Control said:

I wonder if the valves are leaking, can we lap the newer modern engines the same as we could the older engines .... to get the valves to seat?

Sure, these can be lapped in the usual manner, to a certain point, until you need the new valves/seats 😅

1 hour ago, kencombs said:

I am not familiar with that engine, but some of the newer, smaller, especially turbo-charged engines have issue with the PCV systems that cause similar things.

That is true, there is a known condition where the PCV will push some oil into the intake. But my oil appears to be coming from within the combustion chamber itself, unfortunately. The intake manifold is relatively clean, and the issue mainly affects the #1 cylinder, which is literally filling with oil quite rapidly. Some of the other ones are a bit oily too, but not enough to foul the plug and generate a misfire.

1 hour ago, Los_Control said:

right about the 9 minute mark he was talking about a contraption that operates off of oil pressure and controls the lift/duration of your intake valves .... All I know is he said they go bad and are expensive ....  just something I would want to learn more about.

Yes, this is the dreaded multiair brick, which controls the variable valve timing. Mine still works alright and appears to be in good condition. It is sitting underneath the valve cover and has no direct connection to the combustion chamber. It just drives the intake valves, in the usual fashion.

[kencombs]

IF the oil is coming from the intake, either past stems, or in the intake air via the PCV, the back of the valve heads should show signs of that.   I really can't believe that much oil enters the cylinder past the rings with the compression you have, unless the oil ring has failed.   In that case I'd expect to see signs of that on the cylinder walls.

[Ivan_B]

11 hours ago, kencombs said:

In that case I'd expect to see signs of that on the cylinder walls.

True... And the walls look good... 🙄

I don't know, the back of the valves looked dry to me (images shared on the previous page). I'll replace the seals, anyway, already got the valves removed... Also, noticed first problems when cleaning the head: cylinders 1 and 2 have signs of damage from foreign items inside the chamber. No major failure but something was definitely going on in there, at some point 😑 

I have yet to remove and inspect the pistons + rings.